Spas and pools are used in homes, hospitals, hotels, and business for personal relaxation, exercise, and therapy. A spa, or pool, is an investment. Any device that can expand its scope of use makes for a greater return on the investment, while allowing for more activities without requiring more space.
Rowing is often cited as an excellent full-body, but low-impact, form of exercise. But rowing requires a dedicated machine, thereby increasing cost and space requirements.
What is needed is a device that can be installed in an existing spa or pool, allowing it to be used as a rowing machine.